Method for transmitting or receiving signal in wireless communication system, and apparatus therefor

ABSTRACT

A method by which a terminal receives downlink control information in a wireless communication system, according to one aspect of the present invention, comprises the steps of: receiving configurations for a plurality of control resource sets (CORESETs); monitoring control channel candidates in at least one among user equipment-specific search spaces (USSs) and common search spaces (CSSs), which are configured in the plurality of CORESETs; and acquiring control information by monitoring the control channel candidates, wherein the terminal can determine the location of each of the USSs by using specific parameters with respect to each of the plurality of CORESETs to which each of the USSs belongs. The terminal is capable of communicating with at least one of another terminal, a terminal related to an autonomous driving vehicle, a base station or a network.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage application under 35 U.S.C. § 371of International Application No. PCT/KR2018/008962, filed on Aug. 7,2018, which claims the benefit of U.S. Provisional Application No.62/541,786, filed on Aug. 7, 2017. The disclosures of the priorapplications are incorporated by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a wireless communication system, andmore particularly, to a method of transmitting or receiving a downlinksignal and apparatus therefor.

BACKGROUND ART

First, the existing 3GPP LTE/LTE-A system will be briefly described.Referring to FIG. 1, the UE performs an initial cell search (S101). Inthe initial cell search process, the UE receives a PrimarySynchronization Channel (P-SCH) and a Secondary Synchronization Channel(S-SCH) from a base station, performs downlink synchronization with theBS, and acquires information such as a cell ID. Thereafter, the UEacquires system information (e.g., MIB) through a PBCH (PhysicalBroadcast Channel). The UE can receive the DL RS (Downlink ReferenceSignal) and check the downlink channel status.

After the initial cell search, the UE can acquire more detailed systeminformation (e.g., SIBs) by receiving a Physical Downlink ControlChannel (PDCCH) and a Physical Downlink Control Channel (PDSCH)scheduled by the PDCCH (S102).

The UE may perform a random access procedure for uplink synchronization.The UE transmits a preamble (e.g., Msg1) through a physical randomaccess channel (PRACH) (S103), and receives a response message (e.g.,Msg2) for the preamble through PDCCH and PDSCH corresponding to thePDCCH. In the case of a contention-based random access, a contentionresolution procedure such as additional PRACH transmission (S105) andPDCCH/PDSCH reception (S106) may be performed.

Then, the UE can perform PDCCH/PDSCH reception (S107) and PhysicalUplink Shared Channel (PUSCH)/Physical Uplink Control Channel (PUCCH)transmission (S108) as a general uplink/downlink signal transmissionprocedure. The UE can transmit UCI (Uplink Control Information) to theBS. The UCI may include HARQ ACK/NACK (Hybrid Automatic Repeat reQuestAcknowledgment/Negative ACK), SR (Scheduling Request), CQI (ChannelQuality Indicator), PMI (Precoding Matrix Indicator) and/or RI etc.

DISCLOSURE Technical Task

One technical task of the present disclosure is to provide a method oftransmitting/receiving downlink control information and apparatustherefor.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present invention are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present invention could achieve will be more clearlyunderstood from the following detailed description.

Technical Solutions

In one technical aspect of the present disclosure, provided herein is amethod of receiving a downlink control information by a user equipmentin a wireless communication system, the method including receivingconfigurations for a multitude of Control Resource Sets (CORESETs),monitoring control channel candidates in at least one of Userequipment-specific Search Spaces (USSs) and Common Search Spaces (CSSs)configured for a multitude of the CORESETs, and obtaining a controlinformation through the monitoring of the control channel candidates,wherein the user equipment may determine locations of the USSs usingparameters specific to a multitude of the CORESETs to which the USSsbelong, respectively.

In another technical aspect of the present disclosure, provided hereinis a user equipment in receiving a downlink control information in awireless communication system, the user equipment including atransceiver and a processor configured to receive configurations for amultitude of Control Resource Sets (CORESETs) through the transceiver,monitor control channel candidates in at least one of Userequipment-specific Search Spaces (USSs) and Common Search Spaces (CSSs)configured for a multitude of the CORESETs, and obtain a controlinformation through the monitoring of the control channel candidates,wherein the user equipment may be further configured to determinelocations of the USSs using parameters specific to a multitude of theCORESETs to which the USSs belong, respectively.

The user equipment may determine the locations of the USSs respectivelyusing an index C_(k) of a corresponding CORESET in a slot k and a cell-or user equipment group-specific constant.

A multitude of control channel candidates having different aggregationlevels in each of the CSSs may be consecutively disposed withoutoverlapping with each other and disposition order of a multitude of thecontrol channel candidates in each of the CSSs may be determined basedon aggregation levels. For example, a multitude of the control channelcandidates may be disposed in order of a higher aggregation level or alower aggregation level.

Alternatively, a multitude of control channel candidates havingdifferent aggregation levels in each of the CSSs may be inconsecutivelydisposed and each CORESET to which each CSS belongs may be divided intoa multitude of sub-CORESETs. For one example, a single control channelcandidate may be assigned to each of a multitude of the sub-CORESETs andeach of the control channel candidates may be disposed at a front, tail,middle or prescribed offset applied location in each of thesub-CORESETs. For another example, a multitude of the sub-CORESETs maybe related to different aggregation levels, respectively.

Advantageous Effects

According to one embodiment of the present disclosure, since a locationof a USS is determined CORESET-specifically in an environment that amultitude of CORESETs are configured for a user equipment, downlinkcontrol information may be transceived without interference oroverlapping between USSs.

It will be appreciated by persons skilled in the art that the effectsthat can be achieved with the present invention are not limited to whathas been particularly described hereinabove and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings.

DESCRIPTION OF DRAWINGS

FIG. 1 is an exemplary diagram illustrating physical channels used in a3rd Generation Partnership Project (3GPP) Long Term Evolution/Long TermEvolution-Advanced (LTE/LTE-A) system, and a general signal transmissionmethod using the physical channels.

FIG. 2 is a diagram showing one embodiment of a consecutive CSSconfiguring method.

FIG. 3 is a diagram to describe FER performance according to a bundlingsize.

FIG. 4 is a flowchart of a method of transceiving a downlink signalaccording to one embodiment of the present disclosure.

FIG. 5 is a block diagram of a User Equipment (UE) and a Base Station(BS) according to an embodiment of the present invention.

BEST MODE FOR DISCLOSURE

The following description of embodiments of the present invention mayapply to various wireless access systems including CDMA (code divisionmultiple access), FDMA (frequency division multiple access), TDMA (timedivision multiple access), OFDMA (orthogonal frequency division multipleaccess), SC-FDMA (single carrier frequency division multiple access) andthe like. CDMA can be implemented with such a radio technology as UTRA(universal terrestrial radio access), CDMA 2000 and the like. TDMA canbe implemented with such a radio technology as GSM/GPRS/EDGE (GlobalSystem for Mobile communications)/General Packet Radio Service/EnhancedData Rates for GSM Evolution). OFDMA can be implemented with such aradio technology as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, E-UTRA (Evolved UTRA), etc. UTRA is a part of UMTS (UniversalMobile Telecommunications System). 3GPP (3rd Generation PartnershipProject) LTE (long term evolution) is a part of E-UMTS (Evolved UMTS)that uses E-UTRA. 3GPP LTE adopts OFDMA in downlink and adopts SC-FDMAin uplink. LTE-A (LTE-Advanced) is an evolved version of 3GPP LTE.

For clarity, the following description mainly concerns 3GPP LTE systemor 3GPP LTE-A system, by which the technical idea of the presentinvention may be non-limited. Specific terminologies used in thefollowing description are provided to help understand the presentinvention and the use of the terminologies can be modified to adifferent form within a scope of the technical idea of the presentinvention.

As many as possible communication devices have demanded as high ascommunication capacity and, thus, there has been a need for enhancedmobile broadband (eMBB) communication compared with legacy radio accesstechnology (RAT) in a recently discussed next-generation communicationsystem. In addition, massive machine type communications (mMTC) forconnecting a plurality of devices and objects to provide variousservices anytime and anywhere is also one of factors to be considered innext-generation communication. In addition, in consideration of aservice/user equipment (UE) that is sensitive to reliability andlatency, ultra-reliable and low latency communication (URLLC) has beendiscussed for a next-generation communication system.

As such, new RAT that considers eMBB, mMTC, URLCC, and so on has beendiscussed for next-generation wireless communication.

Some LTE/LTE-A operations and configuration that are not at variance toa design of New RAT may also be applied to new RAT. For convenience, newRAT may be referred to as 5G mobile communication.

NR Frame Structure and Physical Resource

In an NR system, downlink (DL) and downlink (UL) transmission may beperformed through frames having duration of 10 ms and each frame mayinclude 10 subframes. Accordingly, 1 subframe may correspond to 1 ms.Each frame may be divided into two half-frames.

1 subframe may include N_(symb) ^(subframe,μ)=N_(symb) ^(slot)×N_(slot)^(subframe,μ) contiguous OFDM symbols. N_(symb) ^(slot) represents thenumber of symbols per slot, μ represents OFDM numerology, and N_(slot)^(subframe,μ) represents the number of slots per subframe with respectto corresponding μ. In NR, multiple OFDM numerologies shown in Table 1below may be supported.

TABLE 1 μ Δƒ = 2^(μ) · 15[kHz] Cyclic prefix 0 15 Normal 1 30 Normal 260 Normal, Extended 3 120 Normal 4 240 Normal

In Table 1 above, Δf refers to subcarrier spacing (SCS). μ and cyclicprefix with respect to a DL carrier bandwidth part (BWP) and μ andcyclic prefix with respect to a UL carrier BWP may be configured for aUE via UL signaling.

Table 2 below shows the number of N_(symb) ^(slot) of symbols per slot,the number N_(slot) ^(frame,μ) of symbols per frame, and the numberN_(slot) ^(subframe,μ) of slots per subframe with respect to each SCS inthe case of normal CP.

TABLE 2 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)0 14 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16 5 14 320 32

Table 3 below shows the number N_(symb) ^(slot) of symbols per slot, thenumber N_(slot) ^(frame,μ) of slots per frame, and the number N_(slot)^(subframe,μ) of slots per subframe with respect to each SCS in the caseof extended CP.

TABLE 3 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)2 12 40 4

As such, in an NR system, the number of slots included in 1 subframe maybe variable depending on subcarrier spacing (SCS). OFDM symbols includedin each slot may correspond to any one of D (DL), U (UL), and X(flexible). DL transmission may be performed in a D or X symbol and ULtransmission may be performed in a U or X symbol. A Flexible resource(e.g., X symbol) may also be referred to as a Reserved resource, anOther resource, or a Unknown resource.

In NR, one resource block (RB) may correspond to 12 subcarriers in thefrequency domain. A RB may include a plurality of OFDM symbols. Aresource element (RE) may correspond to 1 subcarrier and 1 OFDM symbol.Accordingly, 12 REs may be present on 1 OFDM symbol in 1 RB.

A carrier BWP may be defined as a set of contiguous physical resourceblocks (PRBs). The carrier BWP may also be simply referred to a BWP. Amaximum of 4 BWPs may be configured for each of UL/DL link in 1 UE. Evenif multiple BWPs are configured, 1 BWP may be activated for a given timeperiod. However, when a supplementary uplink (SUL) is configured in aUE, 4 BWPs may be additionally configured for the SUL and 1 BWP may beactivated for a given time period. A UE may not be expected to receive aPDSCH, a PDCCH, a channel state information-reference signal (CSI-RS),or a tracking reference signal (TRS) out of the activated DL BWP. Inaddition, the UE may not be expected to receive a PUSCH or a PUCCH outof the activated UL BWP.

NR DL Control Channel

In an NR system, a transmissions NR system, a transmission unit of acontrol channel may be defined as a resource element group (REG) and/ora control channel element (CCE), etc.

An REG may correspond to 1 OFDM symbol in the time domain and maycorrespond to 1 PRB in the frequency domain. In addition, 1 CCE maycorrespond to 6 REGs.

A control resource set (CORESET) and a search space (SS) are brieflydescribed now. The CORESET may be a set of resources for control signaltransmission and the search space may be aggregation of control channelcandidates for perform blind detection. The search space may beconfigured for the CORESET. For example, when one search space isdefined on one CORESET, a CORESET for a common search space (CSS) and aCORESET for a UE-specific search space (USS) may each be configured. Asanother example, a plurality of search spaces may be defined in oneCORESET. For example, the CSS and the USS may be configured for the sameCORESET. In the following example, the CSS may refer to a CORESET with aCSS configured therefor and the USS may refer to a CORESET with a USSconfigured therefor, or the like.

A base station may signal information on a CORESET to a UE. For example,a CORESET configuration for each CORESET and time duration (e.g., 1/2/3symbol) of the corresponding CORESET may be signaled. When interleavingfor distributing a CCE to 1 symbol-CORESET is applied, 2 or 6 REGs maybe bundled. Bundling of 2 or 6 REGs may be performed on 2 symbol-CORESETand time-first mapping may be applied. Bundling of 3 or 6 REGs may beperformed on 3 symbol-CORESET and time-first mapping may be applied.When REG bundling is performed, the UE may assume the same precodingwith respect to a corresponding bundling unit.

Search Space Common Search Space (CSS)

Control channel candidates configuring a CSS may be disposedconsecutively (e.g., consecutive CSS) or inconsecutively (e.g.,distributed CSS).

Consecutive CSS

For example, all candidates required for CSS configuration may bedisposed in a row. ALs of candidates included in CSS are set andcandidates of each AL may be disposed in CORESET. In disposingcandidates configuring CSS, the candidates may be disposed consecutivelywith each other. Regarding the disposed order of candidates in CSS,candidates of the highest AL are first disposed in a row and candidatesof a next higher AL are then disposed in a row [e.g., FIG. 2 (a)]. Onthe contrary, CSS may be configured in order of disposing candidates ofthe lowest AL first and then disposing candidates of a next lower AL[e.g., FIG. 2 (b)]. Alternatively, candidates of each AL may besequentially disposed in descending order [e.g., FIG. 2 (c)] or inascending order [e.g., FIG. 2 (d)]. Alternatively, candidates may bedisposed in a row in a manner of being randomly mixed.

FIG. 2 is a diagram showing one embodiment of a consecutive CSSconfiguring method.

In FIG. 2, an environment of using a search space and PDCCH formatdefined in the current LTE-A is assumed. ALs used in CSS are 8 and 4,and the number of candidates per AL is 2 each.

Distributed CSS

In case of disposing candidates inconsecutively, it is difficult todispose candidates of CSS randomly like USS. As common controlinformation is carried on CSS, since the corresponding common controlinformation needs to be seen by a multitude of UEs, a CSS locationshould be known to all the UEs that need the corresponding commoncontrol information. Therefore, for inconsecutive CSS candidatedisposition, it is necessary to define some rules.

(1) Inconsecutive CSS disposing method 1: The entire region of CORESETis divided into sub-CORESET regions as many as the CSS candidate number,and a single CSS candidate may be disposed in a single sub-CORESETregion. A location of a candidate disposed in each sub-CORESET may beagreed in advance as the head of the sub-CORESET region, the tail of thesub-CORESET region, the middle of the sub-CORESET region, a locationhaving a determined offset value in the sub-CORESET region, etc.

(2) Inconsecutive CSS disposing method 2: The region of CORESET may bedivided into sub-CORESET regions as many as the AL number of CSS. Forexample, if AL 8 and AL 4 are used in CSS, the CORESET region may bemainly divided into two. Candidates for a single AL may be disposed ineach sub-CORESET region. In doing so, the candidates for the single ALmay be disposed consecutively or inconsecutively. When the same ALcandidates are disposed consecutively, they may be disposed at the headof the sub-CORESET region, the tail of the sub-CORESET region, themiddle of the sub-CORESET region, a location having a determined offsetvalue in the sub-CORESET region, etc. When the same AL candidates aredisposed inconsecutively, one sub-CORESET is divided into sub-subCORESETs as many as the number of candidates of the corresponding AL andit may be defined that a single candidate is disposed per sub-subCORESET like the disposing method 1. And, the disposed locations mayinclude the head of the sub-sub CORESET, the tail of the sub-subCORESET, the middle of the sub-sub CORESET, a location having adetermined offset value in the sub-sub CORESET, etc.

(3) Inconsecutive CSS disposing method 3: CSS is disposed across CORESETin the above two methods (1) and (2). Yet, in the method 3, a CORESETregion for disposing CSS therein is preset and CSS may be configured inthe preset region by the disposing method 1 or 2. The region in CORESETfor CSS may be defined as the head of the whole CORESET, the tail of thewhole CORESET, the middle of the whole CORESET, a location having adetermined offset value in the whole CORESET, etc.

(4) Inconsecutive CSS disposing method 4: Bundles, each of which has onecandidate of each AL, are prepared, sub-CORESETs are configured as manyas the number of the corresponding bundles, and candidates may bedisposed therein. If the number of candidates differs per AL, bundles(e.g., N bundles) are first configured with reference to an AL havingthe smallest number of candidates (e.g., N candidates) and the remainingAL candidates may be then assigned to the respective bundles one by one.In doing so, the disposing method 1, 2 or 3 may apply to the bundledisposition in each sub-CORESET.

FIG. 3 shows Frame Error Rate (FER) performance in case of performingREG bundling in a single CCE size and FER performance in case ofbundling all CCEs, for a single AL 8 candidate. In case of the bundlingin CCE size, a method of disposing a candidate at the head of eachsub-CORESET in the disposing method 1 is applied.

Referring to FIG. 3, it may be observed that FER performance in case ofperforming REG bundling in a single CCE size is better than and FERperformance in case of bundling all CCEs.

UE-Specific Search Space (USS) Multi-USS in Multi-CORESET

A single UE may have a multitude of CORESETs configured therefor. Incase that a UE has a multitude of CORESETs, USS may be defined perCORESET. In this case, a different hashing point of the USS may bedefined per CORESET.

For example, although a hashing function for USS is similar to that ofthe existing LTE, a hashing point of USS may be defined different perCORESET. By the hashing function, locations of candidates of the USS maybe defined. In this case, a hashing function may be defined in a mannerthat a hashing point different per CORESET may be derived by applyingspecific information (e.g., CORESET index, etc.) unique to thecorresponding CORESET to the hashing function of determining the hashingpoint.

Formula 1 in the following is a hashing function of a search space inLTE.

$\begin{matrix}{{L\left\{ {\left( {Y_{k} + m} \right){mod}\left\lfloor \frac{N_{{CCE},k}}{L} \right\rfloor} \right\}} + i} & \left\lbrack {{Formula}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In Formula 1, L means an Aggregation Level (AL), m is an integer in arange of 0 to (M^((L))−1), M(L) means the number of candidates of the ALL that should be monitored by a UE in a corresponding search space, andi is an integer in a range of 0 to (L−1). In case of CSS, Y_(k)=0 isdefined. In case of USS, Y_(k)=(A*Y_(k-1))mod D is defined. In case ofLTE, A is 39827. In case of LTE, D is 65537. And, Y⁻¹=n_(RNTI) (e.g., avalue necessary for subframe 0) is defined. the n_(RNTI) may be anidentifier (e.g., radio network temporary identifier) assigned to a UE.

Regarding a factor for determining a hashing point in Formula 1,

plays a great role in changing a hashing point per subframe.

Therefore, according to one embodiment of the present disclosure, byredefining Y_(k), a hashing function of outputting a different hashingpoint per CORESET is defined. For example, by additionally applying twokinds of parameters in Y_(k)=(A*Y_(k-1))mod D, new Y_(k)′ may bedefined. A CORESET index in slot k is defined as C_(k), and a per-cellor -group constant, by which C_(k) is multiplied, is defined as r.Y_(k)′ may be defined as Formula 2.Y _(k)′=(r*C _(k) *A*Y _(k-1))mod D=(A′*Y _(k-1))mod D  [Formula 2]A′=r*C _(k) *A

Referring to Formula 2, although a new variable C_(k) and a constant ris added to Formula 1, Formula 2 has complexity almost similar to thatof the hashing function of the existing LTE. Thus, the hashing functionaccording to Formula 2 has the complexity almost similar to that of thehashing function of the existing LTE and USS of each CORESET may have adifferent hashing point.

Search Space With Multiple TRP/Cell

When a UE is connected to several TRPs/cells and data is transmitted viaa multitude of TRPS/cells, a method of delivering control information onthe corresponding data to a UE is important.

Search Space Allocation for Multiple TRP/Cell

When a single UE is connected to a multitude of TRPs/cells, a searchspace may be configured for a single TRP/cell, a search space may beconfigured for each TRP/cell, or a search space may be configured forsome TRPs/cells only.

Regarding a search space configuring method of each TRP/cell, a methodapplied when a UE is connected to a single TRP/cell is applicableidentically, or a whole search space that a UE may have may beconfigured in a manner of being divided for TRPs/cells.

Alternatively, a search space per TRP/cell may be configured in a mannerof being divided per AL of a search space. For example, if ALsconfigured for a search space are 8 and 4, a search space configured forone TRP/cell may have AL 8 only and another TRP/cell may have a searchspace for AL 4 only. If the number of the connected TRPs/cells isgreater than the number of ALs, there may be a TRP/cell failing to havea search space.

Multiple TRP/Cell in Same Band

When UE-connected TRPs/cells use the same band, a method of configuringa CSS is necessary. If CSSs of TRPs/cells are configured in the sameresource region, there may exist inter-CSS interference.

(1) Offset application: for example, CSSs may be configured not tooverlap with each other in a manner that a resource location configuringa CSS of each TRP/cell has an offset value per TRP/cell. The offsetvalue may be defined by higher layer signaling.

(2) Interleaving application: for another example, interleaving may beapplied to a CSS of each TRP/cell like a USS. For the interleaving,TRP/cell ID, virtual ID and the like may be used. As a result of theinterleaving, resources of different CSSs may overlap with each other inpart. Yet, considering the attribute of the random interleaving,probability of inter-CSS overlapping is not high.

FIG. 4 is a flowchart of a method of transceiving a downlink signalaccording to one embodiment of the present disclosure. FIG. 4 is theexemplary implementation for the above-described embodiments, by whichthe scope of the appended claims and their equivalents is non-limited.And, the aforementioned contents may be referred to for FIG. 4.

A UE may receive configurations for a multitude of Control Resource Sets(CORESETs) [405].

The UE may monitor control channel candidates in at least one ofUE-specific Search Spaces (USS) and Common Search Spaces (CSSs), whichare configured for a multitude of the CORESETs [410].

The UE may obtain control information through the monitoring of thecontrol channel candidates [415].

In some implementations, the UE may determine locations of the USSsusing specific parameters specified for a multitude of the CORESETs towhich the USSs belong, respectively. For example, the UE may determinethe respective locations of the USSs using an index C_(k) of thecorresponding CORESET in a slot k and a cell-specific constant or a UEgroup-specific constant [e.g., Formula 2].

A plurality of the control channel candidates having differentaggregation levels in each of the CSSs may be consecutively disposedwithout overlapping with each other, and the disposition order of amultitude of the control channel candidates in each CSS may bedetermined based on the aggregation levels. For example, a multitude ofthe control channel candidates may be disposed in order of higher orlower levels.

Alternatively, A plurality of the control channel candidates havingdifferent aggregation levels in each of the CSSs may be inconsecutivelydisposed, and each CORESET to which each CSS belongs may be divided intoa multitude of sub-CORESETs. For one example, a single control channelcandidate is assigned to each of a multitude of the sub-CORESETs, andeach control channel candidate may be disposed at the front, tail,middle or prescribed-offset applied location in each sub-CORESET. Foranother example, a multitude of the sub-CORESETs may correspond todifferent aggregation levels, respectively.

FIG. 5 is a block diagram illustrating a structure of a Base Station(BS) 105 and a User Equipment (UE) 110 in a wireless communicationsystem 100 according to an embodiment of the present disclosure. The BS105 may be referred to as an eNB or a gNB. The UE 110 may be referred toa user terminal.

Although one BS 105 and one UE 110 are illustrated for simplifying thewireless communication system 100, the wireless communication system 100may include one or more BSs and/or one or more UEs.

The BS 105 may include a transmission (Tx) data processor 115, a symbolmodulator 120, a transmitter 125, a transmission/reception antenna 130,a processor 180, a memory 185, a receiver 190, a symbol demodulator 195,and a reception (Rx) data processor 197. The UE 110 may include a Txdata processor 165, a symbol modulator 170, a transmitter 175, atransmission/reception antenna 135, a processor 155, a memory 160, areceiver 140, a symbol demodulator 155, and an Rx data processor 150. InFIG. 12, although one antenna 130 is used for the BS 105 and one antenna135 is used for the UE 110, each of the BS 105 and the UE 110 may alsoinclude a plurality of antennas as necessary. Therefore, the BS 105 andthe UE 110 according to the present invention support a Multiple InputMultiple Output (MIMO) system. The BS 105 according to the presentinvention can support both a Single User-MIMO (SU-MIMO) scheme and aMulti User-MIMO (MU-MIMO) scheme.

In downlink, the Tx data processor 115 receives traffic data, formatsthe received traffic data, codes the formatted traffic data, interleavesthe coded traffic data, and modulates the interleaved data (or performssymbol mapping upon the interleaved data), such that it providesmodulation symbols (i.e., data symbols). The symbol modulator 120receives and processes the data symbols and pilot symbols, such that itprovides a stream of symbols.

The symbol modulator 120 multiplexes data and pilot symbols, andtransmits the multiplexed data and pilot symbols to the transmitter 125.In this case, each transmission (Tx) symbol may be a data symbol, apilot symbol, or a value of a zero signal (null signal). In each symbolperiod, pilot symbols may be successively transmitted during each symbolperiod. The pilot symbols may be an FDM symbol, an OFDM symbol, a TimeDivision Multiplexing (TDM) symbol, or a Code Division Multiplexing(CDM) symbol.

The transmitter 125 receives a stream of symbols, converts the receivedsymbols into one or more analog signals, and additionally adjusts theone or more analog signals (e.g., amplification, filtering, andfrequency upconversion of the analog signals), such that it generates adownlink signal appropriate for data transmission through an RF channel.Subsequently, the downlink signal is transmitted to the UE through theantenna 130.

Configuration of the UE 110 will hereinafter be described in detail. Theantenna 135 of the UE 110 receives a DL signal from the BS 105, andtransmits the DL signal to the receiver 140. The receiver 140 performsadjustment (e.g., filtering, amplification, and frequencydownconversion) of the received DL signal, and digitizes the adjustedsignal to obtain samples. The symbol demodulator 145 demodulates thereceived pilot symbols, and provides the demodulated result to theprocessor 155 to perform channel estimation.

The symbol demodulator 145 receives a frequency response estimationvalue for downlink from the processor 155, demodulates the received datasymbols, obtains data symbol estimation values (indicating estimationvalues of the transmitted data symbols), and provides the data symbolestimation values to the Rx data processor 150. The Rx data processor150 performs demodulation (i.e., symbol-demapping) of data symbolestimation values, deinterleaves the demodulated result, decodes thedeinterleaved result, and recovers the transmitted traffic data.

The processing of the symbol demodulator 145 and the Rx data processor150 is complementary to that of the symbol modulator 120 and the Tx dataprocessor 115 in the BS 205.

The Tx data processor 165 of the UE 110 processes traffic data inuplink, and provides data symbols. The symbol modulator 170 receives andmultiplexes data symbols, and modulates the multiplexed data symbols,such that it can provide a stream of symbols to the transmitter 175. Thetransmitter 175 obtains and processes the stream of symbols to generatean uplink (UL) signal, and the UL signal is transmitted to the BS 105through the antenna 135. The transmitter and the receiver of UE/BS canbe implemented as a single radio frequency (RF) unit.

The BS 105 receives the UL signal from the UE 110 through the antenna130. The receiver processes the received UL signal to obtain samples.Subsequently, the symbol demodulator 195 processes the symbols, andprovides pilot symbols and data symbol estimation values received viauplink. The Rx data processor 197 processes the data symbol estimationvalue, and recovers traffic data received from the UE 110.

A processor 155 or 180 of the UE 110 or the BS 105 commands or indicatesoperations of the UE 110 or the BS 105. For example, the processor 155or 180 of the UE 110 or the BS 105 controls, adjusts, and managesoperations of the UE 210 or the BS 105. Each processor 155 or 180 may beconnected to a memory unit 160 or 185 for storing program code and data.The memory 160 or 185 is connected to the processor 155 or 180, suchthat it can store the operating system, applications, and general files.

The processor 155 or 180 may also be referred to as a controller, amicrocontroller), a microprocessor, a microcomputer, etc. In themeantime, the processor 155 or 180 may be implemented by various means,for example, hardware, firmware, software, or a combination thereof. Ina hardware configuration, methods according to the embodiments of thepresent invention may be implemented by the processor 155 or 180, forexample, one or more application specific integrated circuits (ASICs),digital signal processors (DSPs), digital signal processing devices(DSPDs), programmable logic devices (PLDs), field programmable gatearrays (FPGAs), processors, controllers, microcontrollers,microprocessors, etc.

In a firmware or software configuration, methods according to theembodiments of the present invention may be implemented in the form ofmodules, procedures, functions, etc. which perform the above-describedfunctions or operations. Firmware or software implemented in the presentinvention may be contained in the processor 155 or 180 or the memoryunit 160 or 185, such that it can be driven by the processor 155 or 180.

Radio interface protocol layers among the UE 110, the BS 105, and awireless communication system (i.e., network) can be classified into afirst layer (L1 layer), a second layer (L2 layer) and a third layer (L3layer) on the basis of the lower three layers of the Open SystemInterconnection (OSI) reference model widely known in communicationsystems. A physical layer belonging to the first layer (L1) provides aninformation transfer service through a physical channel. A RadioResource Control (RRC) layer belonging to the third layer (L3) controlsradio resources between the UE and the network. The UE 110 and the BS105 may exchange RRC messages with each other through the wirelesscommunication network and the RRC layer.

The above-mentioned embodiments correspond to combinations of elementsand features of the present invention in prescribed forms. And, it isable to consider that the respective elements or features are selectiveunless they are explicitly mentioned. Each of the elements or featurescan be implemented in a form failing to be combined with other elementsor features. Moreover, it is able to implement an embodiment of thepresent invention by combining elements and/or features together inpart. A sequence of operations explained for each embodiment of thepresent invention can be modified. Some configurations or features ofone embodiment can be included in another embodiment or can besubstituted for corresponding configurations or features of anotherembodiment. And, it is apparently understandable that an embodiment isconfigured by combining claims failing to have relation of explicitcitation in the appended claims together or can be included as newclaims by amendment after filing an application.

While the present invention has been described and illustrated hereinwith reference to the preferred embodiments thereof, it will be apparentto those skilled in the art that various modifications and variationscan be made therein without departing from the spirit and scope of theinvention. Thus, it is intended that the present invention covers themodifications and variations of this invention that come within thescope of the appended claims and their equivalents.

As described above, the present disclosure may be applied to variouswireless communication systems.

What is claimed is:
 1. A method of receiving a downlink control information by a user equipment in a wireless communication system, the method comprising: receiving configurations for a multitude of Control Resource Sets (CORESETs); monitoring control channel candidates in at least one of User equipment-specific Search Spaces (USSs) and Common Search Spaces (CSSs) configured for the multitude of the CORESETs; and obtaining a control information through the monitoring of the control channel candidates, wherein the user equipment determines locations of the USSs using parameters specific to the multitude of the CORESETs to which the USSs belong, respectively.
 2. The method of claim 1, wherein the user equipment determines the locations of the USSs respectively using an index C_(k) of a corresponding CORESET in a slot k and a cell -or user equipment group-specific constant.
 3. The method of claim 1, wherein a multitude of control channel candidates having different aggregation levels in each of the CSSs are consecutively disposed without overlapping with each other and wherein disposition order of the multitude of the control channel candidates in each of the CSSs is determined based on aggregation levels.
 4. The method of claim 3, wherein the multitude of the control channel candidates are disposed in order of a higher aggregation level or a lower aggregation level.
 5. The method of claim 1, wherein a multitude of control channel candidates having different aggregation levels in each of the CSSs are inconsecutively disposed and wherein each CORESET to which each CSS belongs is divided into a multitude of sub-CORESETs.
 6. The method of claim 5, wherein a single control channel candidate is assigned to each of the multitude of the sub-CORESETs and wherein each of the control channel candidates is disposed at a front, tail, middle or prescribed offset applied location in each of the sub-CORESETs.
 7. The method of claim 5, wherein the multitude of the sub-CORESETs are related to different aggregation levels, respectively.
 8. A user equipment in receiving a downlink control information in a wireless communication system, the user equipment comprising: a transceiver; and a processor configured to receive configurations for a multitude of Control Resource Sets (CORESETs) through the transceiver, monitor control channel candidates in at least one of User equipment-specific Search Spaces (USSs) and Common Search Spaces (CSSs) configured for the multitude of the CORESETs, and obtain a control information through the monitoring of the control channel candidates, wherein the user equipment is further configured to determine locations of the USSs using parameters specific to the multitude of the CORESETs to which the USSs belong, respectively.
 9. The user equipment of claim 8, wherein the processor determines the locations of the USSs respectively using an index C_(k) of a corresponding CORESET in a slot k and a cell- or user equipment group-specific constant.
 10. The user equipment of claim 8, wherein a multitude of control channel candidates having different aggregation levels in each of the CSSs are consecutively disposed without overlapping with each other and wherein disposition order of the multitude of the control channel candidates in each of the CSSs is determined based on aggregation levels.
 11. The user equipment of claim 10, wherein the multitude of the control channel candidates are disposed in order of a higher aggregation level or a lower aggregation level.
 12. The user equipment of claim 8, wherein a multitude of control channel candidates having different aggregation levels in each of the CSSs are inconsecutively disposed and wherein each CORESET to which each CSS belongs is divided into a multitude of sub-CORESETs.
 13. The user equipment of claim 12, wherein a single control channel candidate is assigned to each of the multitude of the sub-CORESETs and wherein each of the control channel candidates is disposed at a front, tail, middle or prescribed offset applied location in each of the sub-CORESETs.
 14. The user equipment of claim 12, wherein the multitude of the sub-CORESETs are related to different aggregation levels, respectively.
 15. The user equipment of claim 8, wherein the user equipment is capable of communicating with at least one of another user equipment, a user equipment related to an autonomous driving vehicle, a base station or a network. 